[bug] On macOS, when setting the window radius, the WebView does not display the expected radius.

[SpuerMomonga]

Describe the bug

Use the following code to create a window, set a rounded corner for the window, and the window will display the expected rounded corner.

    let effects = tauri::window::EffectsBuilder::new()
        .effects(vec![tauri::window::Effect::WindowBackground])
        .radius(12.0)
        .build();

    let window = tauri::WindowBuilder::new(handle, "main")
        .resizable(true)
        .title("Raykit")
        .min_inner_size(400.0, 400.0)
        .inner_size(750.0, 475.0)
        .center()
        .visible(false)
        .transparent(true)
        .decorations(false)
        .effects(effects)
        .build()?;

In the code below, after adding a webview of the same size to the window, the webview does not display the expected rounded corner effect.

let effects = tauri::window::EffectsBuilder::new()
        .effects(vec![tauri::window::Effect::WindowBackground])
        .radius(12.0)
        .build();

    let window = tauri::WindowBuilder::new(handle, "main")
        .resizable(true)
        .title("Raykit")
        .min_inner_size(400.0, 400.0)
        .inner_size(750.0, 475.0)
        .center()
        .visible(false)
        .transparent(true)
        .decorations(false)
        .effects(effects)
        .build()?;

    window.add_child(
        tauri::WebviewBuilder::new("main-app", tauri::WebviewUrl::App(Default::default())).auto_resize(),
        tauri::LogicalPosition::new(0., 0.),
        tauri::LogicalSize::new(750., 475.),
    )?;

Reproduction

https://github.com/raykit-apps/raykit

Expected behavior

When the window is set with rounded corners, the WebView will also be covered by the rounded corners.

Full tauri info output

[✘] Environment
    - OS: Mac OS 15.6.1 arm64 (X64)
    ✔ Xcode Command Line Tools: installed
    ✘ Xcode: not installed!
    ✔ rustc: 1.87.0 (17067e9ac 2025-05-09)
    ✔ cargo: 1.87.0 (99624be96 2025-05-06)
    ✔ rustup: 1.28.2 (e4f3ad6f8 2025-04-28)
    ✔ Rust toolchain: stable-aarch64-apple-darwin (default)
    - node: 22.18.0
    - pnpm: 10.11.1
    - npm: 10.9.3
    - bun: 1.2.21

[-] Packages
    - tauri 🦀: 2.8.5
    - tauri-build 🦀: 2.4.1
    - wry 🦀: 0.53.3
    - tao 🦀: 0.34.3
    - @tauri-apps/api : not installed!
    - @tauri-apps/cli : 2.8.4

[-] Plugins

[-] App
    - build-type: bundle
    - CSP: unset
    - frontendDist: ../../out
    - devUrl: http://localhost:3000/
    - framework: React

Stack trace

Additional context

No response